It is not possible to set valueAxis properties for StockChart Navigator. If we have a chart as in the attached image, we have the blue line in the main chart and also in the navigator, but they seems different. This is because the valueAxis of the line chart is from 0 to 120000 (from 0 because we have the other violet line with values near 0), whereas the navigator "valueAxis" is from 98000 to 104000 (the same in the main line chart, if we put just the blue line and we remove the violet one).